Due to rapid innovation of transportation technology, plenty of portable transport vehicles are used widely in order to transport things (especially heavy load) from one place to the other. For instance, a movable bed is an indispensable article in a hospital for transporting a patient (who is usually inconvenient to walk by itself) from one place to another, like taking the patient from the ward to an operation room or an X-ray room and vice versa.
Referring to FIG. 1, a perspective view of a conventional hospital bed is shown to include a carrier frame 10, four casters 11 mounted rotatably to four corners of the carrier frame 10, and left and right safety rails 12 mounted at two opposite sides of the carrier frame 10. The safety rails 12 can be lifted upward in order to prevent falling of the patient from the carrier frame 10. Alternately, the safety rails 12 can be lowered to facilitate descending of the patient from the carrier frame 10.
One drawback of the aforesaid conventional hospital bed resides in that the carrier frame 10 needs to be moved manually. Manually moving the carrier frame 10 is laborious, thereby causing inconvenience to the medical staff, who already has to burden overwork due to short stuff. Since the walking path in the hospital is not very large due to limited area, the number of the medical staff moving the carrier frame 10 may block the walking path or cause traffic jam, thereby bringing uncomfortable feelings to the nearby persons who are happened to be around the carrier frame 10.